Electrostatic precipitation is a widely used method for cleaning gasses, having long been used in large scale industrial applications. The fundamental design of electrostatic precipitators remained largely unchanged for years. In a typical application, seen, for example, in U.S. Pat. No. 1,204,907, a high voltage electrode was placed in the center of a grounded tube. The high voltage caused corona discharge between the discharge electrode and the grounded tube which imparted an electrostatic charge to particles in a gas between the discharge electrode and the grounded tube. The charged particles were then precipitated electrostatically onto the surface of the grounded tube, resulting in cleaner gas. While effective, this arrangement necessitated relatively large structures and had the disadvantage of being difficult to clean.
Recent efforts have been directed at adapting electrostatic gas cleaning technology to personal air cleaners sized for use in the home. An example of these efforts can be found in U.S. Pat. No. 6,176,977. This patent is directed to so-called “electro-kinetic” technology. Electro-kinetics takes advantage of the air movement produced by a very high voltage differential across two porous electrode arrays. As with traditional electrostatic precipitation, the voltage differential causes charged particles and surrounding air molecules to move in the direction of the grounded or negatively charged electrode. As the charged particles and air molecules pass through the porous second array of electrodes, which removes some of the particles from the air, at least a portion of the air molecules retain their momentum, resulting in a flow of air past the second array. The displacement of the air causes more air to be drawn into the space between the arrays, and the cycle continues.